The present invention relates to a device for storing and restoring electrical energy.
The invention refers to the field of producing, storing and supplying electricity, including those relating to the field of renewable energy, and more specifically to the field of producing hydrogen and oxygen by water electrolysis and producing electricity by hydrogen and oxygen fuel cells.
The fuel cell is an electrochemical device that converts chemical energy from a fuel into electrical energy. The operating principle of this electrochemical generator is based on the electrochemical synthesis reaction of water from an oxidizer, such as oxygen, and from a fuel, such as hydrogen.
The operating principle of an electrolyzer is the reverse of that of a fuel cell. While the fuel cell combines, by electrochemical reaction, dihydrogen and dioxygen to form water and supply electricity, electrolysis disassociates water into its constituent elements, i.e., into hydrogen and oxygen, and requires electrical supply.
Therefore, associating an electrolyzer with a fuel cell so as to store electrical energy produced by a source and to restore it on demand is known.
This association is especially known for storing electrical energy produced intermittently or not intermittently, for example by renewable sources of energy, such as wind or solar energy, but also by any primary source whatsoever. Therefore, the electrical energy produced by the primary source is transformed by electrochemical reaction, via the electrolyzer, into dihydrogen and into dioxygen, that are then stored under pressure. The dihydrogen and dioxygen are then converted on demand into electrical energy by means of a fuel cell when a customer electrical load needs electricity that the grid cannot supply or when the primary source no longer produces electricity or produces insufficient electricity with relation to the demand from the downstream electrical load or electrical grid. Therefore, if the device is connected to the electrical grid and supplies a customer, said device serves to restore electricity on customer demand when the grid experiences power failures; And if the device is connected to sources of renewable energy, the device is used to restore electricity when the renewable source does not produce electricity or does not produce enough electricity.
The various known systems are generally bulky and require significant space for their installations. They are also not very modular or flexible, particularly as regards the quantity of energy available, or electric capacity, that they are capable of supplying to the customer grid. Lastly, on-site installations are relatively complex and difficult to maintain. All these difficulties thereby limit a widespread distribution of electrolyzer/fuel cell systems in industry.